Abstract

The physiological stress response results in release of glucocorticoid hormones such as corticosterone (CORT). Whereas short-term activation of this response helps animals cope with environmental stressors, chronic activation can result in negative effects including metabolic dysregulation and reproductive failure. However, there is no consensus hormonal profile of a chronically-stressed animal, suggesting researchers may need to look beyond hormone titers to interpret the impacts of chronic stress. In this study, we brought wild house sparrows (Passer domesticus) into captivity. We then compared glucocorticoid and mineralocorticoid receptor concentrations in sparrows exposed either to a standardized chronic stress protocol (n=26) or to standard husbandry conditions (controls; n=20). We used radioligand binding assays to quantify receptors in whole brain, liver, kidneys, spleen, gonads, gastrocnemius and pectoralis muscle, omental and subcutaneous fat, and bib and back skin. In most tissues, CORT receptors did not differ between controls and stressed animals, although we found marginal increases in receptor density in kidney and testis in stressed birds at some time points. Only in pectoralis muscle was there a robust effect of chronic stress, with both receptor types higher in stressed animals. Increased pectoralis sensitivity to CORT with chronic stress may be part of the underlying mechanism for muscle wasting in animals administered exogenous CORT. Furthermore, the change in pectoralis was not paralleled by gastrocnemius receptors. This difference may help explain previous reports of a greater effect of CORT on pectoralis than on other muscle types, and indicate that birds use this muscle as a protein reserve.

Similar articles

Other journals from The Company of Biologists

Many organizations that use sonar for underwater exploration gradually increase the volume of the noise to avoid startling whales and dolphins, but a new Research Article from Paul Wensveen and colleagues reveals that some humpback whales do not take advantage of the gradual warning to steer clear.

Many animals stabilize their vision by swivelling their eyes to prevent the image from smearing as they move. A new Research Article on tadpoles from Céline Gravot and colleagues shows that contrast between objects in their view affects the strength of this visual reflex, suggesting that the eye may be processing the image at a basic level to produce the reflex.

When starting her own lab at James Cook University, Australia, Jodie Rummer applied for a Travelling Fellowship from JEB to gather data on oxygen consumption rates of coral reef fishes at the Northern Great Barrier Reef. A few years later, Björn Illing, from the Institute for Hydrobiology and Fisheries Science, Germany, followed in Jodie’s footsteps and used a JEB Travelling Fellowship to visit Jodie’s lab. There, he studied the effects of temperature on the survival of larval cinnamon clownfish. Jodie and Björn’s collaboration was so successful that they have written a collaborative paper, and Björn has now returned to continue his research as a post-doc in Jodie’s Lab. Read their story here.

Where could your research take you? The deadline to apply for the current round of Travelling Fellowships is 30 Nov 2017. Apply now!